During general anesthesia, temperature monitoring is critical especially in pediatrics. Recently developed 3M™ Bair Hugger™ skin temperature which is applied on temporal artery is correlated with core temperature measure by esophageal prove in several studies. Conventional skin temperature over carotid artery is also correlated with core temperature in several studies. The purpose of this study is comparing 2 methods of temperature monitoring in pediatrics. First, conventional core temperature measure by esophageal stethoscope. Second, 3M™ Bair Hugger™ applying on carotid artery.

Core temperature should be monitored under general anesthesia. Because patients are prone to hypothermia during surgery, besides, pediatric patients are more vulnerable in temperature control. Conventional core temperature is monitored at esophagus, rectum, nasopharynx. But some of them are invasive and impossible in sometimes. Recently developed 3M™ Bair Hugger™ skin temperature which is applied on temporal artery is correlated with core temperature measured by esophageal prove in several studies. Its mechanism is making zero heat flux on skin applied. But it also cannot apply in head or facial surgery. Other studies showed conventional skin temperature over carotid artery is also correlated with core temperature. The investigators hypothesized using 3M™ Bair Hugger™ on carotid artery could be alternative method measuring core temperature. The purpose of this study is comparing 2 methods of temperature monitoring in pediatrics. First, conventional core temperature measure by esophageal stethoscope. Second, 3M™ Bair Hugger™ applying on carotid artery.

Inclusion Criteria:

• scheduled operation under general anesthesia
• Who need esophageal temperature monitoring
• American society of anesthesiology physical status 1 or 2

Exclusion Criteria:

• Body mass index > 35 kg/m2
• Who cannot be inserted esophageal temperature prove
• Patients with fever > 38'C
• History of malignant hyperthermia

Pediatric patients aged 1 to 5 years old who scheduled surgery under general anesthesia. Who need esophageal temperature monitoring for routine monitoring.